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Sains Malaysiana 46(10)(2017):
1987–1995 http://dx.doi.org/10.17576/jsm-2017-4610-38
Variasi Jumlah Kandungan Elektron Ionosfera di Malaysia ketika Solar Minimum (Variations Total Electron Content of Ionospheric in Malaysia
during Minimum Solar) SITI
AMINAH
BAHARI1*,
MARDINA
ABDULLAH1
& BAHARUDIN YATIM2 1Space Science Center,
Institute of Climate Change, Universiti
Kebangsaan Malaysia, 43600 UKM Bangi,
Selangor Darul Ehsan, Malaysia 2Pusat Pengajian Fizik, Fakulti Sains dan
Teknologi, Universiti
Kebangsaan Malaysia, 43600 UKM Bangi,
Selangor Darul Ehsan, Malaysia Received:
8 March 2017/Accepted: 20 September 2017 ABSTRAK Ionosfera merupakan satu
lapisan atmosfera
bumi yang mengandungi elektron bebas dan boleh memberi
kesan ralat
kepada perambatan gelombang elektromagnetik terutama kepada sistem kedudukan global (GPS). Kesan jumlah
kandungan elektron
(TEC)
dan fenomena
melibatkan sistem suria-magnetosfera-ionosfera-termosfera kepada
isyarat satelit
dan komunikasi radio sentiasa berubah.
Kajian ini memfokuskan kepada perubahan TEC ketika aktiviti suria di tahap minimum. Objektif utama kajian ini adalah
untuk mengkaji
variasi TEC di rantau
Malaysia terhadap masa harian,
perubahan musim,
aktiviti suria dan medan
magnet bumi. Isyarat GPS yang disebarkan pada dua frekuensi
jalur L1 dan
L2 mengandungi data kod dan fasa membolehkan
pengiraan TEC diperoleh
menggunakan GPS. Data
GPS
pada tahun
2007 yang diperoleh daripada
Jabatan Ukur
dan Pemetaan Malaysia (JUPEM),
digunakan dalam
kajian ini. Hasil kajian di Asia Tenggara menunjukkan ketika musim ekuinoks, nilai purata TEC dicatatkan tinggi iaitu 35 TEC unit (TECU)
berbanding dengan
nilai purata TEC pada soltis
yang mencatatkan bacaan
25 TECU.
Aktiviti suria
didapati lebih memberi kesan kepada
perubahan TEC berbanding
dengan medan
magnet bumi dengan
faktor kolerasi antara aktiviti suria adalah lebih
tinggi iaitu
0.64 berbanding dengan medan magnet bumi iaitu 0.34 sahaja. Kajian ini tertumpu
ketika aktiviti
suria di tahap minimum dengan keadaan medan magnet bumi
secara puratanya
adalah senyap. Ini seterusnya membolehkan hasil kajian ini
menjadi asas
kepada maklumat mengenai ionosfera di Malaysia. Kata kunci: GPS; ionosfera;
solar minimum ABSTRACT The ionosphere is a
layer in the Earth’s atmosphere where free electrons exist in
sufficient numbers to affect the propagation of electromagnetic
waves especially the Global Positioning System (GPS) signals. The ionosphere is also
known as ‘space weather laboratory’ as it is directly affected
by any activity in space. The influence of the total electron
content (TEC)
and physical phenomenon regarding the sun-magnetosphere-ionosphere-thermosphere
system on satellite and radio communication is constantly changing.
The study of the TEC variation in ionosphere and structures is important
to ensure the security of radio communication systems, to enhance
the currently restricted global ionospheric mapping and accurate
space weather forecasting. This paper focused on the variation
of TEC during solar minimum. The
main objective of this research was to study the variation of
TEC over
Malaysia on diurnal, seasonal solar and geomagnetic activity
using GPS.
Since the GPS signals are broadcasted in two widely spread L-band
frequency channels L1 and L2 consisting of code and phase, it
is possible to determine the TEC using GPS. To achieve this objective,
GPS
data for year 2007 was obtained from the Department
of Survey and Mapping Malaysia (JUPEM) were used in this research. The
results over South East Asia showed that the mean TEC during
equinox was higher than solstice, whereby 35 TECU was
recorded during the equinoxes but only 25 TECU was
observed during solstice. It was found that solar variation
had more effects on the variation of TEC as compared to the geomagnetic variation.
The correlation factor for solar variation was higher, that
is 0.64 but yielded only 0.34 for geomagnetic variation. This
research was carried out during solar minimum and quiet geomagnetic
conditions. Therefore, the results from this research can be
used as a reference for the characterization of ionosphere in
Malaysia. Keywords: GPS; ionosphere; minimum
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